This invention relates to the prevention of fouling in a basic solution which is in contact with a gaseous or liquid hydrocarbon stream.
In cracking operations, such as in the pyrolytic cracking of ethane, propane, and naphthas to form olefins, oxygenated compounds, including carbonyl compounds, are formed. The amount of carbonyl compounds, such as aldehydes and ketones, formed in such operations can vary widely, but is typically about 1-100 ppm in the gas stream with concentrations as high as 1000 ppm occasionally being encountered because of the utilization of various feedstocks and cracking temperatures. When the gas stream is passed through a basic wash (pH&gt;7) to remove acidic components such as hydrogen sulfide and carbon dioxide, oxygen containing compounds, such as the carbonyl functionality compounds, are also removed. These oxygen containing compounds, particularly acetaldehyde, will undergo polymerization in the presence of the basic wash or scrubbing conditions. In the wash tower, the resulting polymer will settle on the trays leading to fouling and eventual plugging of the trays, which means the unit must be shut down for cleaning -- obviously a costly operation. The basic wash systems, where treatment is required to inhibit such polymer-based fouling, include amine acid gas scrubber (e.g., MEA, DEA, isopropyl amine, butyl amine, etc.) and caustic wash systems.